Download Spinal Cord

Psyc 372 – Physiological Psychology
Overview
• Has a central core of non-myelinated
neurons (gray matter) surrounded by
myelinated neurons (white matter)
• Gray matter is shaped like an H
• Is shorter than the vertebral column
• Is separated into regions which contain
structures.
Spinal Cord
Psychology 372
Physiological Psychology
Steven E. Meier, Ph.D.
Listen to the audio lecture while viewing these slides
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Dorsal
Funiculus
Psyc 372 – Physiological Psychology
Spinal Cord
Dorsal Horn
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Psyc 372 – Physiological Psychology
Some Structures
• Dorsal Horn
• Contains sensory nuclei
• Forms clusters of nuclei
• Receives information from outside the CNS
Lateral
Funiculus
• Ventral Horn
Lateral
Corticospinal
Tract
Ventral Horn
Ventral
Funiculus
• Contains motor nuclei
• Receives information from major motor
pathways
• Sends information to muscles
• Does not contain clusters – are arranged in
columns that run the length of the spinal cord
Ventral Corticospinal Tract 3
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Psyc 372 – Physiological Psychology
Psyc 372 – Physiological Psychology
Some Structures
Internuncial Neurons
• Are different sizes depending on where
you are in the spinal column.
• E.g.
• Also called interneurons
• Are also in gray matter
• Modulate information flowing from
sensory neurons towards the brain, and
higher brain centers to motor neurons
• Modulates neural activity within motor
systems.
• Are also involved in reflexes.
• Ventral horn is larger where motor
neurons innervate the arms and legs.
• Need neurons for regulation
• Dorsal Horn is larger where sensory
nerves from the limbs enter the spinal
cord.
• Need more neurons because you have
more receptors.
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Psyc 372 – Physiological Psychology
Psyc 372 – Physiological Psychology
White Matter
Dorsal Column
• Surrounds the Gray Matter
• Divided into three columns
• Lie between the two dorsal horns
• Sends only sensory information via
axons to the brain
• Uses the Gracile Fasciculus (lower
limbs) and Cuneate Fasciculus (upper
body) pathways.
• Dorsal
• Lateral
• Ventral
• Each column contains bundles of
ascending and descending axons
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Dorsal
Funiculus
Psyc 372 – Physiological Psychology
Dorsal Column
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Gracile Fasciculus
Psyc 372 – Physiological Psychology
Cuneate Fasciculus
Lateral Columns
Dorsal Horn
• Sends information to the brain
• Also sends information from the
brainstem and cortex to lower motor
neurons.
• Lateral Corticospinal tract.
Lateral
Funiculus
Lateral
Corticospinal
Tract
Ventral Horn
Ventral
Funiculus
• Sends motor information to Final
Common Pathway
• Most motor information is sent in this
pathway.
Ventral Corticospinal Tract 9
Psyc 372 – Physiological Psychology
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Psyc 372 – Physiological Psychology
Ventral Columns
Ventral Columns
• Includes ascending and descending
axons
• Ascending sends information about pain
and thermal sensation.
• Descending pathways help control axial
muscles and posture.
• Uses Ventral Corticospinal tract and
others
•
Sends remaining motor information
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Psyc 372 – Physiological Psychology
Psyc 372 – Physiological Psychology
Spinal Cord
Cervical Nerves
• Divided into four major regions
• Has 8 segments
• Involved with
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Cervical
Thoracic
Lumbar
Sacral
• sensory perception
• Motor function on the back of the head,
neck, arms
• Are related to body development
segments
• Nerves enter and leave through the
intervertebral foramen.
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Psyc 372 – Physiological Psychology
Psyc 372 – Physiological Psychology
Thoracic
Lumbar and Sacral
• Has 12 segments
• Innervates upper body
• Lumbar - 5 segments
• Sacral - 5 segments
• Innervates the lower body, the back,
and legs
• Spinal Cord usually terminates in the
lumbar area.
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Psyc 372 – Physiological Psychology
Psyc 372 – Physiological Psychology
Pyramidal Decussation
Other Things
• Located in the Medulla
• Is where the majority of fibers cross
over to the opposite side of the body
• Few sensory axons enter at sacral level
• As you ascend up the spinal column,
more sensory neurons enter.
• Most descending axons terminate at
cervical levels
• Thus, the sacral level has less white
matter than at cervical levels.
• E.g., 80-85% of motor fibers cross over
to contralateral (opposite) side
•
Uses the lateral corticospinal tract
• 15-20% remain ipsilateral (on same
side)
•
Uses the ventral corticospinal tract.
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